Hey Guys,

I swapped in a 4L80e last weekend and I'm still working out some kinks. Before installing the trans we did a TransGo HD2 kit and now the tranny slips in all gears. It has no problem shifting, runs smooth, and doesnt slip under light throttle. When anything more than light throttle is applied the tranny will slip. I think this is due to a very light line pressure. When installing the kit I only drilled the holes out to .96", which they describe as 'firm' shifts.

Has anyone seen this after installing a shift kit? Does anyone have any insight as to what may have gone wrong during the install, or what could possibly cause this?

 

I'm going to go a manual pressure test to see what line pressure is... now I just have to find a gauge and figure this one out haha

 

Perhaps the pressure relief valve they supply in the kit is malfunctioning. I was told not to use it because it can cause more headeaches. I went with a Sonnax self regulating boost valve instead.

 

hmmm... that could be a problem seeing as I already drilled the hole.

Truthfully when we did the shift kit we forgot to install the relief valve but punched the hole for it earlier in the night... it was a LOOONG night so I'm not surprised we goofed up. I thought for sure that was the culprit for the problems I was having. I went back in, pulled the pan and installed the relief valve last night, but it drives the same for the most part. Now I'm thinking there must have been another problem, but I hadnt really considered the fact that it could be that assembly still causing a problem.

 

There's two holes you need to drill in the valve body for the TG pressure relief.

If it drove the same before the valve then it's probably not the issue. Definitely measure the line pressure, pretty easy with the port on the side.

 

You could have already burned the fwd clutches, did you make sure the pressure relief valve seated in the hole? As already mentioned many people omit that step and go the Sonnax route, mine has a Sonnax valve also.

 

I don't think the clutches will be damaged. I've been extremely light on it from the get go as I was trying to 'break in' the converter per yanks instructions. When I drive it I barely get past 2k while accelerating to cruising speeds just so nothing slips in the process.

Also the fluid I have drained has been very clean.

If I did damage them then shame on me... Another lesson from the school of hard knocks.

 

Damn bud this sucks , don't get discouraged though , it will all work out .

I was thinking exactley what Pat was , I hope the low psi didn't help burn your clutches . Retrace your steps carefully , the directions in that kit aren't very specific , my only gripe about transgo. Pat and I know a great trans guy who may be able to offer some advice .

 

ill bet its that stupid relief valve assembly i took my time and double checked everything when doing the shift kit install even though i did forget to put the plate back on

hey it was 5:30am

 

When doing step 5 did you seat the valve in the hole?